knockturn alley
Just around the corner from Diagon Alley lies a dark, twisting alleyway devoted to the Dark Arts: Knockturn Alley. Not only are the wares sold there somewhat dangerous, but the wizards and witches hanging around behave fairly suspiciously as well. From the shops and the street vendors one can purchase, among other things, shrunken heads, poisonous candles, human-looking fingernails, and Flesh-Eating Slug Repellent.